Commutator



United States Patent U.S. Cl. 310228 3 Claims ABSTRACT OF THE DISCLOSURE A disk commutator including a rotatable support member of insulating material having embedded radially spaced commutator segments. The support member has a circular recess in one face thereof, adapted to receive a fixed pair of electrical contacts for successive engagement with the commutator segments, and to maintain lateral alignment of the contacts during rotation. The support member is further provided with a radial recess extending from the circular recess to the edge of the support member for the centrifugal discharge of particles from the circular recess. As an additional feature, the commutator segments extend radially from the support member and are provided with clamping portions at the ends thereof. Elongated raised surfaces are provided on the commutator segments, and the clamping portions to securely retain the respective lead wires to the commutator segments after clamping.

This invention relates to commutators for electric motors, and more particularly to an improved face commutator for use in very small electric motors.

Small motors, such as the type utilized in cameras, toys, etc., are typically nonrepairable due to their low cost construction, and the effective life of such motors is usually equal to the life of the weakest part which, in many instances, is the commutator. The required small size and low cost of the commutator introduces a number of operational and structural problems or limitations which tendto reduce the expected life of the commutator and motor assembly. One problem is that of securely attaching the motor winding wires to the commutator using low cost techniques. In the case of a rotatable commutator another problem is the ditficulty of maintaining alignment of an extremely small fixed contact with the commutator segments during rotation. Still another problem is the difiiculty of preventing metal and other particles such as those resulting from commutator and contact Wear, from shorting the commutator segments or otherwise resulting in poor electrical contact.

It is a principal object of the present invention to provide an improved commutator for small electric motors which is not subject to the aforementioned limitations.

Another object of the invention is to discharge particles, such as those resulting from frictional wear from the electrical contact region of a commutator during operation of the commutator.

Another object of the invention is to continuously maintain alignment of a fixed contact with the commutator segments of a commutator during rotation of the commutator.

Another object of the invention is to provide improved means for attaching lead wires to the contact segments of a commutator.

In the disclosed embodiment of the invention, a face commutator comprises a body of insulating material having commutator segments fixed thereto in radially spaced relationship. The body defines a circular recess in one side thereof adapted to receive and align a fixed contact 3,486,056 Patented Dec. 23, 1969 with the commutator segments during rotation of the commutator. The body is further provided with a recess extending from the circular recess to the edge of the body for movement of particles from the circular recess during rotation of the commutator. As an additional feature, the commutator segments extend radially from the body and are provided with clamping portions at the ends thereof adapted to be bent over to clamp lead wires between said segments and said clamping portions. Elongated raised surfaces are provided on the segments and clamping portions to securely retain the lead wires to the segments.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a front view of a face commutator in accordance with the invention;

FIG. 2 is a section taken along the line 22 of FIG. 1;

FIG. 3 is a rear view of the commutator shown in FIG. 1;

FIG. 4 is a fragmentary side view of the commutator shown in FIG. 1;

FIGS. 5 and 6 are enlarged details illustrating the method of attaching lead wires to the commutator segents.

Referring to the drawings, the disclosed embodiment of the invention more specifically comprises a body 10 which may be formed from insulating material such as plastic, and which may have the circular configuration illustrated in FIGS. 1 and 3. The body 10. defines a central opening or bore 12 adapted to receive a shaft (not shown) of an electric motor (not shown). The opening 12 may be provided with radially spaced flats 14 as indicated in FIGS. 1 and 2, for the purpose of keying the body 10 to a motor shaft (not shown), having a complemental configuration.

A plurality of radially spaced commutator segments 16 are supported by the body 10 in the pattern illustrated in FIGS. 1 and 3'. For example, the commutator segments 16 may be imbedded in the body 10 by suitably supporting the segments 16 in the spaced relationship shown, and molding the body 10 to said segments using known plastic molding techniques. Suitable supporting and molding techniques are within the capabilities of those skilled in the art and further description is deemed to be unnecessary.

As shown in FIGS. 1 and 2, the body 10 is preferably shaped to define a circular recess 18 in one side surface thereof, which extends to the surfaces of the commutator segments 16 whereby the exposed surfaces of the commutator segments define the bottom surface of the recess 18. In the disclosed embodiment of the invention, the recess 18 is formed by molding the body 10 to define a pair of spaced circular flanges 20 and 22 (FIG. 1) On the side of the body 10, in concentric relationship with the opening 12, the annular space between the flanges defining the recess 18.

The recess 18 is arranged to receive a fixed spring contact 24 Which may be supported ina manner well known in the art to be sequentially engaged by the commutator segments 16 during rotation of the commutator. While for simplicity only one contact 24 has been shown it will be apparent to those skilled in the art that in actual practice of the invention more than one contact may be used. During such operation the juxtaposed annular surfaces of the flanges 20 and 22 serve to maintain alignment of the contact 24 with the surfaces of the commutator segments 16 within recess 18, to insure positive uniform engagement of the contact 24 with the commutator segments. This feature of the invention reduces the possibility of erratic motor operation resulting from contact misalignment and contributes to increased motor efliciency and longer commutator life.

As shown in FIGS. 1 and 4 the outer flange 22 is provided with a radial slot 26 in the surface thereof, having a bottom surface in the same plate as the bottom surface of the commutator segments. The slot 26 is provided to permit movement of particles out of the recess 18. Such particles may, for example, be present in the recess 18, as a result of frictional wear of the commutator segments 16, contact 24 and surfaces of the recess 18.

During rotation of the commutator, the particles will be displaced from the recess 18 through slot 26 by centrifugal force, and thus will be effectively discharged from the recess 18. This feature prevents particles resulting from frictional wear from interfering with electrical contact, and also contributes to more eflicient motor operation and longer motor life.

--The body 10 is further provided with a plurality of radially spaced recesses 27 in the rear side thereof which are aligned with the gap between adjacent commutator segments. The recesses 27 also assist in maintaining the contact area clear and provide for air circulation between the commutator segments to produce a cooling effect.

Referring now more specifically to the commutator segments 16, these parts extend radially from the body 10 and define generally V-shaped portions for attachment of lead wires extending from the motor windings (not shown). The end leg segment 28 of each V-shaped portion is adapted to be bent toward the other leg segment 30, to

clamp a lead wire therebetween. As shown more clearly in FIG. l, the leg segments 28 and 30 of each V-shaped portion, have generally rectangular cross sections shaped or modified to define elongated raised surfaces 32 and 34 on the juxtaposed faces thereof respectively which serve to firmly engage and securely retain a lead wire.

Referring to FIG. one of the V-shaped portions is illustrated in enlarged detail with a lead wire 36 positioned to be clamped, while FIG. 6 illustrates the positions of the parts after clamping of the wire 36. When the parts are positioned as shown in FIG. 5, clamping of the wire 36 is accomplished by applying a force to leg segment 28 sufiicient to cause bending displacement of leg segment 30 ;into engagement with body 10, and bending displacement of leg segment 28 toward segment 30 to securely clamp and pinch the wire 36 between the surfaces 32 and 34.,As will be observed in FIG. 6, the surfaces 32 and 34 and the wire 36 flatten slightly at the point of engagement in response to the applied clamping force. This deformation insures positive retention of the wire 36 between the leg segments 28 and 30. It will be apparent that the wire 36 is securely retained by the combined clamping and pinching action of the surfaces 32 and 34.

If the lead wires attached to the tangs 28 in the above described manner have an insulating film or coating on the surface thereof, the insulating coating may be removed from the area of contact with surfaces 32 and 34 by heat staking, i.e. applying an electrical voltage to the connection of magnitude sufficient to melt the coating.

The particular shape of the surfaces 32 and 34 and the small contact area thereof in addition to increasing the clamping action, facilitates the removal of the wire insulatjng coating by heat staking. The small contact area reduces the voltage required to a minimum, and insures complete removal of the coating from the wire surfaces engaged by the raised surface 32 and 34. While one ormore of the preferred embodiments of the invention have been herein shown and described, it will be apparent to those skilled in the art that many modificationsv of the structure and arrangement of parts disclosed may be made within the scope of the invention as defined in the appended claims I claim:

1. A face commutator adapted to be mounted on a rotatable shaft of an electric motor for cooperation with a pair of electrical cont-acts of the motor, comprising:

supporting means of insulating material comprising a central opening for receiving the shaft and defining a circular walled recess surrounding said opening in spaced concentric relationship therewith, and an additional recess extending radially outward from said circular recess for the discharge of particles from said circular recess during rotation of said supporting means; and

a plurality of radially spaced, electrically conductive commutator segments fixed to said supporting means and. having portions thereof extending within said recess and adapted upon rotation of said supporting means to be successively engaged by the contact pair extending within said recess.

2. A face commutator adapted to be mounted on a rotatable shaft of an electric motor for cooperation with a pair of electrical contacts of the motor, comprising:

disk supporting means of insulating material, comprising a central opening for receiving the shaft, and spaced inner and outer circular flanges on one face thereof, concentrically arranged with respect to said central opening, said outer flange comprising a radial recess in the surface thereof to facilitate centrifugal discharge of particles from the space between said flanges; and

a plurality of radially spaced, electrically conductive commutator segments supported in said disk supporting means and having portions thereof extending in the space between said flanges, and upon rotation of said disk supporting means adapted to be engaged successively by the contact pair extending 1 within the space between said flange.

3. A face commutator adapted to be mounted on the shaft of an electric motor for cooperation with a pair of electrical contacts of the motor, comprising:

a disk member of plastic material comprising a central opening for receiving the shaft;

a plurality of radially spaced, electrically conductive commutator segments molded with said disk member and adapted to successively engage the contact pair upon rotation of the commutator;

a pair of spaced circular flanges on one face of said disk member comprising a circular recess adapted to laterally align the contact pair during rotation of the commutator; and

a radial recess in one of said flanges for the dynamic discharge of particles from said circular recess.

References Cited UNITED STATES PATENTS 351,167 10/1886 Diehl 310-237 1,525,967 2/1925 Vogel 310-233 2,658,158 11/1953 Bender 310-234 2,897,385 7/ 1959 Powell 310-234 3,010,182 11/1961 Quinlan 310-235 3,014,144 12/1961 Fleischmann 310-237 3,253,172 5/1966 Taylor 310-235 3,223,869 12/ 1965 Reisnecker 310-234 3,244,917 4/1966 Gute 310-237 3,309,548 3/ 1967 Gough 310-234 O'RIS L. RADER, Primary Examiner L. L. HEWITT, Assistant Examiner US, l, X-R. 310-237, 242 

